Improved method of removing obstructions from oil-wells



NITED STATES PATENT OFFICE.

'W. G. SHERWOOD, OF BUFFALO, NEV YORK.

.IMPROVED METHOD OF REMOVING OBSTRUCTIONS FROM OIL-WELLS.

Specification forming part of Letters Patent No. 57,982. dated September11, 1866.

To all whom it may concern:

Be it known that I, WILLIAM (J. SHERWOOD, of the city of Buffalo, countyof Erie, and State of New York, have invented a new and improved methodof cleaning oil-wells and other deep Artesian wells from obstructionsoccasioned by drills, reamers, or other tools or tubing which may becomebroken, wedged, or otherwise fastened in the well; and I do herebydeclare that the following, is a full and exact description of suchinvention and improvelnen t.

The nature of my invention consists in the application and use ofsulphuric acid or its equivalent admitted into the well in a manner tobring the acid in contact with the obstructing tool, so that the acidwill eat away, corrode, or decompose and destroy the tool, or loosen itsufficiently so that it may be removed easily by the use of ordinarygrappling devices.

To enable others skilled in the art to understand and use my invention,I will proceed to describe it. v

It is well known to persons engaged in sinking or boring oil and otherdeep wells that the drill, reamer, or other tool usedfor such purposefrequently breaks, leaving the broken part in the well, or the toolbecomes wedged or so firmly fastened in the rock as to resist allmethods heretofore known to remove it. This necessitates an abandonmentof the well ata great loss of time and money, because the boring cannotproceed nor the well be made available until the obstruction is removed.This fact has been shown in many instances within a few years past inthe extensive boring or sinking of petroleum-oil wells, and there arenow many thousands of dollars wasted in these obstructed wells which maybe recovered by the application and use'of my improvement.

The eorroding and decomposing action of sulphuric acid upon iron andsteel is well known, and if this or any equivalent acid can be broughtin contact with the obstructing tool or other obstruction in the well,its action upon the tool or other thing, to corrode, eat

away, and thereby loosen it, or to wholly decompose and destroy it, iscertain.

The only difficulty to be encountered is to get the acid in contact withthe obstructing tool; and this maybe accomplished in several ways. Oneway is to let down into the well a small tube till its lower end reachesthe obstructing tool, and then to admit through this tube a sufficientquantity of acid to eat away, corrode, and loosen or wholly destroy thetool or other obstruction. Another way is to provide a glass bottle orcylinder of less diameter than the bore of the well, so that it willeasily pass into the well, and till this bottle with acid, and thenlower it into the well by means of a suitable rope or chain, so thatwhen the bottle strikes the tool it will break and empty its acidcontents upon the obstructing tool. Another way is to provide a copperbarrel vof less diameter than the bore of the well, and

of sufficient length to hold a gallon (more or less) of acid, having avalve in the bottom with a stem projecting downwardly. This copperbarrel is then filled with acid and lowered into the well by a suitablerope or chain until the projecting valve-stem strikes the ob structingtool. This will open the valve and allow the acid to be dischargeddirectly onto the obstructing tool, and the copper barrel may then bedrawn up and filled, and again used in the same well, if need be, and inother wells. Other analogous plans may be used.

The acid thus applied will trickle down and get between the obstructingtool and the rock, and will soon corrode or eat away from the outersurface thereof sufficient to loosen it, so that if ordinarygrappling-tools are then used the obstructing tool may be drawn up andremoved; but if such grappling-tools are not at hand a larger quantityof acid may be used, and its action continued until the obstructing toolis entirely decomposed and destroyed. The acid will also act upon therock, and will decompose portions thereof in which the tool is wedged,and thereby quicken and render more easy this method.

To prevent any injurious effects of the acid which is thus put into thewell upon new tools which may he subsequently used to complete theboring of the well, I immediately neutralize it, after the obstructingtool is removed, by introducing into the Well alkali or otherneutralizing liquids. These neutralizing liquids may be put into thewell by the same means as are used for the admission of the acids, andthen the whole of these substances may be pumped out withoutanyinjurious effects from the acid.

Sulphuric acid, on account of its cheapness. and rapid action, will bestmeet the purpose of this method; but my method also contem-

